Polyesters from disulfonyl dicarboxylic acids and esters



3,077,466 Patented" Feb. 12,- I963 3,077,466 POLYESTERS FROM DISULFONYLDICAR- BOXYLIC ACIDS AND ESTERS John R. Caldwell, Russell Giikey, andWinston J. Jackson, Jr., Kingsport, Tenn., assignors to Eastman KodakJQompany, Rochester, N.Y., a corporation of New ersey No Drawing. FiledOct. 7, 1955, Ser. No. 539,268

Claims. (Cl. 260-75) 'Ihis invention relates to high melting crystallinelinear polyesters of primarily aliphatic character which can be preparedby condensing (a) an aliphatic disulfonyldicarboxylic compoundcontaining two symmetrically placed sulfonyl groups separated by apolymethylene radical, with (b) a glycol. The condensation process isessentially the same as the procedural techniques now well example,Carothers and Hill in 1932 described,'among others, polyethylenesebacate which melts at about 75 C., and polyethylene succinate whichmelts at about 97 C. These polyesters are typical of the linearaliphatic polyesters. Moreover, linear polyesters from aliphaticsulfonyl dicarboxylic acids are also of generallylow melting character.For example, a linear polyester from ethylene glycol and4,4-sulfonyldibutyric acid melts at about 8090 C; and hence is of novalue as a molding plastic, a film, or a fiber. One commonly used way ofproducing higher melting polymeric compositions using such aliphaticacids is to condense them with polyfunctional compounds so as to formcross-linked polymers w'hich are not linear in character. For example,an

aliphatic sulfone acid can be condensed with a poly amine containing twoprimary amino groups and one or more secondary amino groups. suchaliphatic sulfone acids in high melting polymers is to employ such acidsmerely as modifiers in polymeric compositions which depend for theirhigh melting points upon other constituents.

It has now been discovered that linear polyesters having substantiallyno cross linking and characterized by unusually high melting points andhigh crystallinity can be prepared by employing a disulfonyldicarboxyliccompound (acid or ester) wherein the two sulfonyl radicals are separatedby at least two carbon atoms and the carboxyl radicals are separatedfrom the sulfonyl radicals Another way of using by at least 3 carbonatoms. This is quite unexpected in view of the teachings and inferencesof the prior art.

It is an object of the invention to provide new linear polyestersderived from the disulfonyldicarboxylic compounds defined by the generalformula set forth hereinbelow.

A further object of the invention is to provide polyester compositionsderived from these disulfonyldicarboxylic compounds which have highmelting points, are crystalline, and can be advantageously employed forthe manufacture of films, fibers, extruded objects, molded shapes, etc.

An additional object of the invention is to provide new fibers derivedfrom a novel polyester which fibers can be dyed to practical shades atatmospheric pressurewith cellulose acetate dyes.

A still further object of the invention is to provide orcolor-typephotographic emulsions of silver halides, gelatin, etc.

Another objectof the invention is to provide novel aliphaticdisulfonyldicarboxylic acids as defined by the general formula set forthhereinbelow.

A further object of the invention to provide a process for preparingthese novel disulfonyldicarboxylic acids.

These and other objects which will appear hereinafter can be achieved inaccordance with the invention described herein.

According to one embodiment of the invention, 'the noveldisulfonyldicarboxylic compounds having the following fiormula areprovided:

R OOC-'-RSO CH --S Oy-R-CO 0R wherein x represents an integer of from 2to 4, R represents a radical selected from the group consisting of a (CHand a C(CH --CH radical, and R represents a substituent selected fromthe group consis t ing of a hydrogen atom and an alkyl radicalcontaining from 1 to 6 carbon atoms.

According to another embodiment of the invention these noveldisulfonyldicarboxylic compoundscan be prepared by the following seriesof reactions wherein x represents either 2;3 or'4:

0H, scnzomcmo 0 0 can):

(CH2) s oHioHicHzcooH All steps are characterized by good yields. Thisproc-L ess of the invention is valuable for the production of4,4'-polymethylenesulfonyld-ibu-tyric acids and their esters,

which can be used as intermediates in the manufacture;

of polyesters and polyamides. The esters can also be used asplasticizers for cellulose derivatives and vinyl polymers byincorporating a minor proportion of such plasticizers in celluloseacetate, cellulose nitrate, poly vinyl chloride, polymeric methylmethacrylate, etc.

The following procedures illustrate a preferred manner of practicingthis embodiment of this invention but are not intended to limit theinvention 'unless' otherwise specifically indicated:

EXAMPLE "1 Step (1A .-Ethyl 4-Mercaptobutyrate (a New Compound) Asolution containing 300 g. of potassium hydroxide in- 1200 cc. ofmethanol was cooled in an ice water bath and saturated Withhydro-gensulfide. While hydrogen sulfide was slowly bubbled into thisstirredsolution, 780 g. of ethyl 4-bromobutyrate was added at such arate that the temperature did not rise above 25. The

reaction mixture was stirred at 25 for 2 hr. (hydrogen sulfidecontinuously added), and then the potassium bromide was removed byfiltration. The filtrate was diluted with 2 1. of water and the product(lower layer) collected. The potassium bromide residue was thoroughlywashed with isopropyl ether and this ethereal solution was then used forextracting the aqueous solution. The product, combined with the etherealsolution, was washed with water, dried with sodium sulfate, anddistilled. The mercapto ester, B.P. 68-70/5 mm. 11 1.4580, was obtainedin yields of 80-85% (475-500 g.).

Step (13 .4,4'-Ethylenedithiodibutyric Acid, Diethyl Ester (a NewCompound) An alcoholic solution of sodium ethoxide was prepared bydissolving 25.3 g. (1.1 moles) of sodium in 450 cc. of absolute ethanol.This solution was then cooled, and 155 g. (1.05 moles) of ethyl4-mercaptobutyrate was slowly added. While the solution was cooled in anice water bath, 94 g. (0.50 mole) of ethylene dibromide was slowly addedwith stirring (very exothermic reaction). The mixture was then refluxedwith stirring for 2 hr. The sodium bromide could not be filtered sinceit was in colloidal form. When the mixture was diluted with water, theproduct separated as an upper layer. it was taken up in isopropyl ether,and the aqueous solution was extracted with isopropyl ether. Thecombined ether solutions were washed with water, dried with sodiumsulfate, and concentrated under reduced pressure ('100/3 mm). The orangeresidual oil weighed 145 g. (90% yield).

Step (1C) .4,4'-EthyZenedithiodibutyric Acid New Compound) To 145 g. ofthe crude 4,4-ethylenedithiodibutyric acid, diethyl ester dissolved in400 cc. of hot acetic acid was added 56 cc. of sulfuric acid in 216 cc.of water. This solution wa-s refluxed for 7 hr. while the ethyl acetatewhich formed was continuously distilled od. When the solution cooled,the product crystallized. This was collected, washed with water, andrecrystallized from 1400 cc. of Water. Transparent platelets (90 g., 75%yield) were obtained, M.P. 104-106". Neutral equivalent: Calcd: 133.Found: 133.

Step (JD).-4,4'-EthyZenedisulfonyldibutyric Acid (a New Compound) Astirred solution containing 72 g. of ethylenedithiodibutyric acid in 400cc. of acetic acid was slowly treated with 136 g. of 30% hydrogenperoxide. An ice water bath kept the temperature down to 50-60". Thesolution was then refluxed with stirring for 1 hr. During this time theproduct began crystallizing. It was collected and washed with ethanol;yield 86.5 g. (97%), M.P. 220-224. Recrystallization from 870 cc. of 88%formic acid gave 83 g. of tiny white crystals melting at 221- 224.5

Analysis.-C-alcd. for C H O S S, 19.41. S, 19.47.

Found Step (1E) .4,4-Ethylenedisulfonyldibutyric Acid, Dimethyl Ester (aNew Compound) Recrystallization from 4 l. of methanol The above esterwas hydrolyzed to the dibasic acid as in Example 1. This new acid meltedat 94-95". Neutral equivalent: Calcd. 140. Found: 140.

Step (2D).--4,4'-Trimcthylenedisulfonyldibutyric Acid (a New Compound)The above dithiodibutyric acid was oxidized to the disulfonyl compoundwith hydrogen peroxide in a pro cedure similar to that in Example 1. Theproduct melted at 238240. Analysis.-Calcd. for C I-1 8 0 S, 18.62.Found: 18.37.

Step (2E ).4,4-Trimethylcnedisulfonyldibulyric Acidj Dimetlzyl Ester (aNew Compound) The disulfonyldibutyric acid was esterified with methanol(p-toluenesulfonic acid catalyst) by heating for 4 hr. in a rockingautoclave at The product, recrystallized from water, consisted ofcolorless plates melting at 164-165".

Analysis.-Calcd, for (1 11 5 0 S, 17.22. Found: 8, 17.23.

EXAMPLE 3 Steps (3A-D).-4,4'-Tetramethylenedisulfonyldibutyric Acid ((1New Compound) In a manner similar to that in Example 1 (IA-D) thiscompound was prepared starting with ethyl 4-mercaptobutyrate andtetramethylenc chloride.

Analysis.Calcd. for O l-1 0 5 S, 17.89. Found: 17.96.

Step (3E).4,4-TeirnmethylenedisulfonyIdibutric Acid Dimethyl Ester (aNew Compound) The above acid was esterified with methanol by the methodused in Example 2.

S Analysis-Calcd. for C H O S S, 16.59. Found:

Other species within the above general formula defining these noveldisulfonyldicarboxylic compounds can be similarly prepared by employingthe isomers or homologs of the compounds used in the preceding examples.

According to an other embodiment of the invention thedisulfonyldicarboxylic compounds defined above can be converted intohigh melting, crystalline, linear polyesters by a process whichcomprises condensing at least one of these compounds with a glycolcontaining from 2 to 12 carbon atoms employing the procedural techniqueswhich are now well known in the art relating to the preparation oflinear high melting polyesters of this general type.

The techniques described in the prior art are generally set forth inconnection with the employment of an aromatic dibasic acid or ester butthey are equally applicable to the employment of thedisulfonyldicarboxylic. acid or ester thereof with which this inventionis primarily concerned.

It is generally advantageous to employ the disulfonyldicarboxylic acidin the form of its lower 'alkyl diesters such as the methyl, ethyl, orbutyl esters. However, the free acids can also be employed by preferablyfirst heating such an acid with an excess of the desired glycol in orderto esterify the carboxyl groups of the free acid.

The condensation reaction is advantageously conducted at a temperaturefrom about to about 250 C. in an inert atmosphere. During the course ofthe condensation reaction the pressure is advantageously reduced to forma vacuum whereby a highly polymeric product can be advantageouslyproduced.

The preparation of these polyesters can be most advantageously carriedout in the presence of a condensation catalyst of the ester interchangetype. These catalysts have been set forth in considerable detail in theprior art and are all believed to be effective tothe preparation ofpolyesters covered by the present invention. Preferred catalysts aretitanium compounds, tin compounds, and aluminum compounds. Especiallyadvantageous catalysts are defined in copending applications Serial Nos.313,072, 313,075, 313,077, and 313,078 filed on October 3, 1952, by I.R. Caldwell et al., which applications have now issued as.U.S. Patents2,720,502 (Oct. 11, 1955), 2,727,881 (Dec. 20, 1955), 2,720,506, (Oct.11, 1955) and 2,720,507 (Oct. 11, 1955), respectively.

In addition to the melt polymerization of polyesters as referred toabove, another well-known technique consists of the preliminaryformation of aprepolymerby carrying out the, process described above toa point where the molten polyester is only sufficiently polymerized .tohave an inherent viscosity of about 0.1 to about 0.3, more ;or less. Theprepolyme-r is then advantageously cooled .to a solid, ground to apowder and further polymerized by heating the powder in an inertatmosphere with stirring at a gradually increasing temperature which isnot sutficiently high to conglomerate the powdered particles. heating iscontinued to a temperature generally well above about 200 C. until aninherent viscosity of the desired value is obtained. A vacuum may beemployed, if desired, but is not essential.

The glycols which can be advantageously employed in the preparation ofthe polyesters covered by this invention include ethylene glycol,trimethylene glycol, other polymethylene glycois containing up to about12 carbon atoms including 2,2-dimethyl-1,3-propanediol and othergem-dialkyl glycols. In addition, cyclic aliphatic giycols and aromaticglycols can also be employed. A cyclic aliphatic glycol of unusual valueis 1,4-cyclohexane dimethanol. The aromatic glycols which can beemployed have the hydroxyl radicals attached to one' or more methyleneradicals. which separate the hydroxyl radicals from the aromaticstructure from which the aromatic glycol was derived. It isespeciallyadvantageous in most instances to employ the aliphatic glycols.containing from i 1 to 6 carbon atoms.

The disulfonyldicarboxylic compounds which can be employed in accordancewith this invention can be supplemented by the addition of one or moredifie-rent aliphatic or aromatic dicarboxylic acids or esters so as toobtain interpolyesters which are modified by the charac- I teristics ofthe added dicarboxylic compound. These added dicarboxylic compound aregenerally employed in the form of their diesters such as the lower alkyldiesters containing from 1 to 6 carbon atoms. Examples of such modifyingcompounds include succinic acid esters, adipic acid esters, sebacic acidesters, dimethylmalonic acid esters, p,p-sulfonyldibenzoic acid esters,terephthalic acid esters, 1,2-di(p-carboxyphenoxy)ethane esters,p,p'-diphenic acid esters,1,2 di(p-carboxyphenyl) ethane esters,4,4-benzo-phenonedicarboxylic acid esters, etc.

By employing various modifying acids and/or glycols the polyestersproduced in accordance with this invention can be made to acquire anydesired wide range of melting This 6 EXAMPLE 4 Three hundred andfifty-eight grams (1.0 mole) of 4,4?

ethylenedisulfonyl dibutyric acid, dimethy'l ester and 1241 g. (2.0mole) of ethylene glycol were placed in a reac tion vessel equipped witha stirrer, a distillation column, and an inlet for purified nitrogen. Aslurry of 0.1g.

active titanium dioxide in 10 ml.,of butyl alcohol was:

Methyl alcohol:

applied. After 23 hours of stirring under vacuum, a viscous melt wasobtained. The vacuum was broken to nitrogen and the polymer allowed tocool in an atmos phere of purified nitrogen. Theinherent viscosity ofthe polyester, as determined in a solution of 60 phenol-409'tetrachloroethane, was 0.61. Determination of the crystalline meltingpoint on the hot stage of a microscope undercrossed Nicols gave a valueof 195l97 C.

This polyester is especially valuable for the production offilm andfibers by the melt-extrusion process.

The

polymer is highly crystalline so that it can be heat set afterorientation to give clear, flexible films with a high heat distortiontemperature and fibers with a high softeningpoint.

EXAMPLE 5 Three hundred and seventy-two grams (1.0 mole) of4,4'-trimethylenedisulfonyl dibutyric acid, dimethyl ester and 124 g.(2.0 mole) of ethylene glycol were placed in a reaction vessel asdescribed in Example 4. A solution of 0.08 g. titanium tetrabutoxide in10 ml. of butyl alcohol a was added as catalyst; After heating at 190400C. for

1 hour the ester interchange was practically complete and. the methylalcohol removed by distillation. The tern-- perature was raised to 240C. and after -15 minutes,-a'

vacuum of 0.2 mm. was applied. A viscous meltwas obtained after 2 hoursunder vacuum with constant stirring. Thepolymer was allowed to cool inan atmosphere of purified nitrogen and then granulated. The inherentviscosity was 0.75 and the crystalline melting point,

218-222 C. The polymer was white in color.

This polyester is especially valuable for the production,

of fibers by the melt spinning process. The filbers draw and heat seteasily and dye with cellulose acetate dyesj EXAMPLE 6 Three hundred andeighty six grams 1.0 mole) of The heating schedule described i inExample 2 was followed. The inherentviscosity of the product was 0.58and. the crystalline melting point, I -189" C. Fibers drawn from themelt drafted well and onrheating become highly crystalliner The productwas valuable as a photographic film base.

EXAMPLE 7 Four hundred and eighty-four grams (1.0 mole) of. 3,3trimethylenedisulfonyl dipivalic acid, dibutyl ester and 208 g. (2.0mole) of 2,2-dimethyl-1,3-propanedi0l were placed in a reaction vesselas described in Example 4. A'solution of 0.05 g. magnesium titaniumbutoxide in 10 ml. butyl alcohol was added as catalyst. The stirredreaction mixture was heated at 220 C. for 2 hours during which time thebutyl alcohol evolved was Ire moved by distillation. The temperature wasraised to 250 C. and maintained there forl5 minutes.

reaction mixture was poured into ice water. The preE polymer thus formedwas dried and ground to'a powder.

Avacuum j of 0.1 mm. was then applied for 10 minutes and the aovzaee Ithad an inherent viscosity of 0.2. The powdered prepolymer was furtherpolymerized by heating in a flask at 200 C. for 4 hours with stirringunder vacuum of 0.1 mm. The final polymer had an inherent viscosity of0.96.

EXAMPLE 8 A polyester having the composition: 1 mole4,4'-trimethylenedisulfonyl dibutyric acid +1 mole trimethylene glycolwas prepared according to the procedure in Example 5. It had an inherentviscosity of 0.72 and was useful for the manufacture of films andfibers.

EXAMPLE 9 EXAMPLE 10 A copolyester having the following composition wasprepared: 0.8 mole 4,4'-trimethylenedisulfonyldibutyric acid +0.2 moleterephthalic acid +1.0 mole ethylene glycol. This product was useful inthe manufacture of films and fibers.

EXAMPLE 11 A copolyester having the following composition was prepared:0.2 mole 3,3'-trirnethylenedisulfonyl dipivalic acid +0.8 moleterephthalic acid +1 mole ethylene glycol. It was used in the productionof fibers which dyed readily with cellulose acetate dyes.

Other valuable polyesters can be similarly prepared as taught in themore general description of the invention given above. These polyestersare unexpectedly high melting and have excellent receptivity to dyes sothat fibers thereof are of especially great utility for the manufactureof fabri s, clothing, etc.

The structure of the polyesters of this invention comprise repeatingunits having the following formula:

wherein R represents the radical obtained by removing both hydroxylgroups from a glycol containing from 2 to 12 carbon atoms, x representsan integer of from 2 to 4, each R represents a radical selected from thegroup consisting of a -(CH radical and a We claim:

1. A process for preparing a 'high melting, crystalline, linearpolyester of substantially aliphatic character which comprisescondensing at a temperature of from about 175 C. to about 250 C. in aninert atmosphere in the presence of a condensing agent (a) an aliphaticdisulfonyldicarboxylic compound having the following general formula:

wherein x represents an integer of from 2 to 4, each R represents aradical selected from the group consisting of a (CH radical and a C(CHCH radical, and each R represents a substituent selected from the groupconsisting of a hydrogen atom and an alkyl radical containing from 1 to6 carbon atoms, with (b) a glycol selected from the group consisting of(l) a polymethylene glycol containing from 2 to 12 carbon atoms, (2) agem-dialkyl polymethylene glycol containing from 5 to 12 carbon atoms,(3) a cyclic aliphatic glycol containing from 6 to 12 carbon atoms, and(4) an aromatic glycol containing from 8 to 12 carbon atoms wherein thetwo hydroxyl radicals are each attached to a methylene radicalinterposed between the hydroxy radical and the aromatic structure.

y 2. A process as defined in claim 1 wherein the condensation is carriedout at a temperature of from about C. to about 250 C. employing a vacuumduring the latter part of the condensation.

3. A process as defined in claim 2 wherein an ester interchange catalystis employed as a condensing agent.

4. A process as defined in claim 3 wherein the disulfonyl-dicarboxyliccompound has the following formula:

R ooc cn s0 (C 2)2 SO -(CH -COOR and the glycol is ethylene glycol.

5. A process as defined in claim 3 wherein the disulfonyl-dicarboxyliccompound has the following formula:

and the glycol is ethylene glycol.

6. A process as defined in claim 3 wherein the disulfonyl-dicarboxyliccompound has the following formula:

and the glycol is ethylene glycol.

7. A process as defined in claim 3 wherein the disulfOIlYLdlCEIbOXYllCcompound has the following formula:

and the glycol is 2,2-dimethyl-1,3-propanediol.

8. A process as defined in claim 3 wherein the disulfonyl-dicarboxyliccompound has the following formula:

and the glycol is trimethylene glycol.

9. A highly polymeric, crystalline, high melting linear polyesterconsisting essentially of a series of repeating units having thefollowing formula:

wherein R represents the radical obtained by removing both hydroxygroups from a glycol containing from 2 to 12 carbon atoms selected fromthe group consisting of (1) a polymethylene glycol containing from 2 to12 carbon atoms, (2) a gem-dialkyl polyrncthylene glycol containing from5 to 12 carbon atoms, (3) a cyclic aliphatic glycol containing from 6 to12 carbon atoms, and (4) an aromatic glycol containing from 8 to 12carbon atoms wherein the two hydroxyl radicals are each attached to amethylene radical interposed between the hydroxy radical and thearomatic structure, x represents an integer of from 2 to 4, and each Rrepresents a radical selected from the group consisting of a -(CHradical and a C(CH -Cl-I radical, said series of repeating units beingterminated at the carboxyl end with an R radical and at the R end with ahydroxyl radical, R being a member selected from the group consisting ofa hydrogen atom and an alkyl radical containing from 1 to 6 carbonatoms.

10. A polyester as defined in claim 9 wherein at is 2, each R representsa -(CH radical and R is an ethylene radical.

11. Polyesters defined in claim 9 wherein x is 3, each R represents a(CH radical and R is an ethylene radical.

12. A polyester as defined in claim 9 wherein x is 4, each R representsa (CH radical and R represents an ethylene radical.

13. A polyester as defined in claim 9 wherein x is 3, each R representsa C(CH -CH radical and R represents a 2,2-dimethyl-1,3-propyleneradical.

14. A polyester as defined in claim 9 wherein x is 3, each R representsa -(CH radical and R represents a trimethylene radical.

9 15. A highly polymeric crystalline, high melting linear polyesterconsisting essentially of a series of repeating units having thefollowing formula:

wherein x represents an integer of from 2-4 and where R'" is divalenthydrocarbon radical of 2-10 carbon atoms in which any cyclic structureis separated from each of the indicated valences of --R"- by a methylenegroup only.

References Cited in the file of this patent UNITED STATES PATENTSLangkammerer Jan. 22, 1946 Whitehill Sept. 16, 1947 Jones Oct. 16, 1951Gregory et a1. July 8, 1952 Caldwell Oct. 14, 1952 FOREIGN PATENTS GreatBritain Mar. 25, 1949

1. A PROCESS FOR PREPARING A HIGH MELTING, CRYSTALLINE, LINEAR POLYESTEROF SUBSTANTIALLY ALIPHATIC CHARACTER WHICH COMPRISES CONDENSING AT ATEMPERATURE OF FROM ABOUT 175* C. TO ABOUT 250* C. IN AN INERTATMOSPHERE IN THE PRESENCE OF A CONDENSING AGENT (A) AN ALIPHATICDISULFONYLDICARBOXYLIC COMPOUND HAVING THE FOLLOWING GENERAL ORMULA: